The present invention relates to the field of jacks for trailer tongues, in particular, to a motorized and directionally steerable trailer tongue jack that may propel a trailer in a plurality of directions.
Vehicle trailers are used in a plethora of applications, ranging from the largest multi-axle commercial trailers weighing many thousands of pounds, to small, single axle trailers weighing only a few hundred pounds that may be towed behind regular passenger cars. These trailers share a common trait. While they may be relatively maneuverable when properly coupled to the towing vehicle, they can be cumbersome to move, even a few feet, when they are not coupled to a towing vehicle, and especially if they are loaded and therefore heavy. Additionally, such trailers frequently need to be coupled and decoupled to a towing vehicle, or perhaps a plurality of different towing vehicles. In order to accomplish this coupling, the tow vehicle, trailer, or both; need to be moved into approximation, and then the tongue of the trailer must be raised over the vehicle hitch, and then lowered and locked into place on the hitch.
This maneuver is both exacting and difficult. Trailers are traditionally equipped with a wheeled tongue jack, such as the jack seen in U.S. Pat. No. 4,511,159 (""159) to Younger, entitled xe2x80x9cTrailer Hitch Guide Assembly.xe2x80x9d The traditional trailer tongue jack, as seen in FIGS. 3 and 4A of the ""159 patent, is fixed to the frame of the trailer in the trailer tongue area The jack has a hand crank to raise and lower the trailer tongue off and onto the vehicle trailer hitch, which is generally a ball type device, and the trailer jack rides upon a caster wheel. The trailer is meant to be pushed on its main load bearing wheels and the caster wheel in order to move the trailer.
The process of coupling a trailer to a tow vehicle is exacting. The vehicle and trailer hitches must be approximated no more than about an inch or two of lateral separation. This is difficult to do by backing the tow vehicle, and a heavily laden trailer, even one of modest size, can be extremely difficult to move manually. While decoupling may be somewhat easier, as the trailer needs only to be cranked up off of the trailer vehicle hitch and the vehicle driven away, it is extremely difficult to move a trailer that is decoupled from its tow vehicle. The trailer is heavy, and at least several hundred pounds of xe2x80x9ctongue weightxe2x80x9d traditionally rests on the trailer jack wheel. Heavy and potentially dangerous physical exertion may be required, and the tow vehicle, trailer, or trailer contents may be damaged by uncontrolled movement.
Various methods have been attempted in simplification of this process. There have been passive guides, such as those seen in U.S. Pat. No. 5,529,330 (""330) to Roman and U.S. Pat. No. 6,234,510 (""510) to Hammons, which are designed to aid in the proper alignment of a backing tow vehicle, so as to guide the approximation of the tow vehicle and trailer. The aforementioned ""159 device of Younger acts to pull a trailer tongue laterally after the tow vehicle and trailer are placed in relatively close approximation.
Attempts have been made at improving the approximation process. For example, U.S. Pat. No. 5,016,900 (""900) to McCully provides a plurality of cranks and worm gears to allow vertical and lateral motion of the trailer tongue, and rotational movement of the trailer jack caster wheel. This concept suffers from a number of drawbacks. Firstly, the necessarily small size of the gears makes the mechanical advantage of the device low, and therefore it would be difficult for one of moderate or limited physical ability to use the device with trailers of appreciable weight. In particular, turning of the caster is accomplished with no gear advantage at all, but through a turning bar seen best in FIG. 1 at element 46. Secondly, the cranks each activate movement in only a single plane, therefore, to move the trailer in more than one plane, the operator must first adjust one crank, then another, and then yet another, in order to bring the tow vehicle and the trailer into approximation. Thirdly, the rack and pinion nature of the trailer tongue elevating means, seen best in FIG. 1 at elements 28 and 30, necessitates that the trailer tongue weight is carried on at most one or two teeth of the rack and pinion. Such an arrangement is inherently susceptible to wear or breakage of the teeth, or jamming due to the ingress of foreign objects into the gear mechanism.
U.S. Pat. No. 3,861,482 (""482) to Stephens et al. is similarly configured, with the addition of a coil spring under load from the trailer tongue weight, seen best in FIG. 9 as element 80, and a gasoline engine to power the wheel, seen best in FIG. 9 as element 70. Such a design is even more cumbersome in steering than the ""900 device, as the user of the ""482 device must hand crank for elevation, hand manipulate a steering bar, and control a gasoline engine attached to the wheel. Additionally, the ""482 device employs the structurally suspect rack and pinion method of adjusting height.
Similarly, U.S. Pat. No. 4,860,841 (""841) to Sacco, while using two directional motors, retains the deficient hand cranking height adjustment seen in the other patents cited that results in both difficult cranking for many individuals and a failure to truly be able to mechanically steer the trailer tongue as to both lateral and vertical directions.
Accordingly, the art has needed a means for moving a laden trailer into position behind a tow vehicle, raising the trailer tongue against several hundred pounds of tongue weight, and lowering the trailer tongue hitch onto the corresponding hitch of the tow vehicle. During removal, such means require raising the trailer tongue off of the vehicle hitch, again against several hundred pounds of tongue weight, lowering the trailer tongue into a storage position, and possibly moving the trailer a short distance in any one of several directions for storage. These maneuvers should be accomplished in a smooth and controlled manner with a minimum of physical exertion or danger to the operator. The instant invention accomplishes these, and other, ends.
In its most general configuration, the present invention advances the state of the art with a variety of new capabilities and overcomes many of the shortcomings of prior devices in new and novel ways. In its most general sense, the present invention overcomes the shortcomings and limitations of the prior art in any of a number of generally effective configurations.
In one of the numerous configurations, the invention generally comprises a height adjustment system, a steering system, a drive system, a mounting plate, and a control system. The mounting plate releasably joins the present invention to any of the wide variety of trailers commonly pulled by vehicles. The height adjustment system includes a power transmission screw that serves as the backbone of the present invention. The power transmission screw is secured to the drive system at one end and proceeds to pass through the height adjustment system, the mounting plate, and the steering system. The power transmission screw engages the height adjustment system through the threaded receipt in a power sleeve nut, and engages the steering system via receipt in a steering sleeve that fixes the relative position of the screw and the sleeve.
The height adjustment system is joined to the mounting plate by a nut support. The nut support contains a nut support bearing system, the power sleeve nut, and a sleeve nut bearing system. The internal surface of the power sleeve nut has an engagement region that is threaded to cooperate with the thread of the power transmission screw. The power sleeve nut transfers the load from the mounting plate to the power transmission screw. The power sleeve nut is rotated about the power transmission screw by the driving gear powered by an actuator. As the driving gear rotates the power sleeve nut around the power transmission screw, the steering system, the mounting plate, and the height adjustment system, with the exception of the power transmission screw, move vertically up and down the power transmission screw. In a preferred embodiment the power transmission screw and the power sleeve nut cooperate to form a self-locking system that prevents movement in relation to each other while under no influence from the driving gear. In a further variation, the height adjustment system further includes a failsafe follower nut working in conjunction with the power sleeve nut such that upon failure of the power sleeve nut the load is automatically transferred to the failsafe follower nut. The failsafe follower nut and the power sleeve nut rotate together but only the power sleeve nut carries the load during normal operation.
The steering system includes a steering sleeve, having an internal surface and an external surface, a driving gear, an actuator, a steering sleeve bearing system, and a cover. The steering sleeve is adapted to receive the power transmission screw and fix the relative position of the steering sleeve and the power transmission screw, generally through the use of a keyway. The steering sleeve and the power transmission screw are rotated by the driving gear powered by the actuator.
The drive system is adapted to be secured to the power transmission screw and imparts translation motion on the jack and the trailer. The drive system includes a wheel in contact with a rolling surface, generally the ground, whereby the wheel is configured to rotate within a wheel housing, about an axle, and is powered by an actuator that is attached to the wheel housing.
The control system is adapted to control the translation of the trailer, the direction of translation of the trailer, and the tongue height of the trailer. The control system may include a user pendent operatively connected to the jack. The user pendent may be wired, or wireless. In a further embodiment the entire control system may be automated such that when the jack is within a predetermined distance from the desired hitch, the jack guides itself to be in close proximity to the hitch. One such method may include a portable wireless transmitter and a transceiver. The transmitter may be formed to mount on hitch of a tow vehicle and emit a guidance signal and the transceiver receives the guidance signal and automatically controls the translation, direction of translation, and the tongue height.
These variations, modifications, alternatives, and alterations of the various preferred embodiments, arrangements, and configurations may be used alone or in combination with one another as will become more readily apparent to those with skill in the art with reference to the following detailed description of the preferred embodiments and the accompanying figures and drawings.